High pressure dosing apparatus, especially for grinding and polishing machines

ABSTRACT

A high pressure dosing apparatus includes a housing with a chamber for receiving material to be dispensed. A dispensing output is controlled by a control valve which operates in response to pressure within the chamber so that the outlet is opened only when the pressure within the chamber exceeds a given level. A pressure generating means for controlling pressure within the chamber includes a pressure operated piston having a piston rod extending into the chamber. A pair of stops are provided for limiting the movement of the piston in opposite directions.

United States Patent Westenberger May 28, 1974 [54] HIGH PRESSURE DOSING APPARATUS, 3,250,247 5/1966 Beaman 239/453 X POLISHING MACHINES 3,653,596 4/l972 Abrams ct al. 239/93 [76] Inventor: Walter Westenberger, 3,705,687 l2/l972 Vincemini 239/92 Kittelerstrasse l 1, D-605l Laemmerspiel, Germany Primary ExaminerM. Henson Wood, Jr. [22] Filed; Jam 29, 1973 Assistant Examiner lohn J. Love Attorney, Agent, or Firm-W0lfgang G. Passe; Roberts [21] Appl. No: 327,763 Willard w [30] Foreign Application Priority Data [57] ABSTRACT Z germany A high pressure dosing apparatus includes a housing many with a chamber for receiving material to be dispensed. [52] us CL 239/533 239582 A dispensing output is controlled by a control valve [51] Int. CL BOSb 1/30 which operates in response to pressure within the [58] Field 331 332 chamber so that the outlet is opened only when the '6 452454 pressure within the chamber exceeds a given level. A pressure generating means for controlling pressure within the chamber includes a ressure operated is- [56] References Cited ton having a piston rod extending into the chamber? A UNITED STATES PATENTS pair of stops are provided for limiting the movement l,8l 1,73l 6/1931 Petty 239/533 UX of the piston in opposite directions 3,101,906 8/1963 Webber 239/600 X 3,246,625 4/1966 Beaman 239/453 X 14 Claims, 5 Drawing Figures I HIGH PRESSURE DOSING APPARATUS, ESPECIALLY FOR GRINDING AND POLISHING MACHINES BACKGROUND OF THE INVENTION The present invention relates to a high pressure dosing apparatus, especially for applying a grinding or polishing paste to the polishing member or carrier in grinding and polishing machines. It will be understood, of course, that the invention is not limited to this application of a dosing machine.

Known high pressure dosing devices of one type work, for example, by means of air pressure in such a manner that the paste is sprayed onto the polishing carrier intermixed with air.

High pressure dosing devices are also known which operate by means of high pressure and by means of which it is possible to supply the grinding or polishing medium without intermixing it with air. In both of these prior art devices or methods it is rather difficult to precisely dose the quantity of paste to be applied to the polishing medium carrier. Furthermore, it is a disadvantage of the prior art spray which is intermixed with air that a substantial proportion of the medium to be applied does not reach the polishing or grinding disk, but rather contributes to soiling of the polishing or grinding machine. Devices operating with high pressure also necessitate special safety precautions, which ineral maintenance.

OBJECTS OF THE INVENTION In view of the foregoing it is the aim of the invention to achieve the following objects singly or in combination:

to provide a device of simple construction which is capable of precisely dosing the paste to be applied and which avoids the intermixing of the polishing paste with air while nevertheless permitting the use of very high pressures;

to provide a high pressure dosing apparatus of the type employing pressure from a pressure source for controlling the dispensing of a material in precise quantities, in which pressure for dispensing material from a supply chamber of the material is coupled to the chamber by way of a pressure operated piston having limiting stops, so that precise quantities of material may be dispensed from the chamber without intermixing of the material with air; and

to provide a high pressure dosing apparatus for automatically dispensing precise quantities of a material, which may be readily and cleanly operated even though the material is dispensed by means of a pressure source.

SUMMARY OF THE INVENTION In order to solve the above problem, according to the invention, a housing is provided including a supply chamber for containing the medium to be dosed or applied to a grinding or polishing carrier. The supply chamber has an inlet opening which is closable by a back pressure relief valve and an outlet opening which is closable by a control valve. The control valve is controlled by the pressure present in the supply chamber. A pressure generator is provided having a piston. The

stroke of the piston is adjustable between two stops, the piston producing the pressure in the supply chamber and consequently displacing a dosed quantity of the polishing medium out of the supply chamber.

With the pressure generator according to the invention it is possible to obtain a pressure translation ratio, and this in turn results in very high working pressures. The use of adjustable stops for the piston of the pressure generator makes it possible to precisely dose the quantity to be discharged. Furthermore, since the out put opening of the supply chamber is opened and closed by a valve which is controlled directly by the pressure prevailing in the supply chamber, it is possible to construct the apparatus according to the invention with a few structural elements and these elements cooperate with each other in a most simple manner.

In order to assure that the control valve opens properly in response to the pressure prevailing in the supply chamber, the portion of the nozzle pin inside the supply chamber is provided with a surface which is subjected to the pressure prevailing in the supply chamber in order to move the nozzle pin in the valve opening direction. This surface is preferably located adjacent to the free end of the nozzle pin, and it is preferably that portion of the nozzle pin surface which extends directly away from the valve seat into the inner space of the supply chamber. The free end of the nozzle pin may, for example, have a conical tip or it may have a ball shape.

BRIEF FIGURE DESCRIPTION In order that the invention may be clearly understood, it will now be described, by way of example, with reference to the accompanying drawings, wherein:

FIG. 1 is a sectional view through one embodiment according to the invention;

FIG. 2 is a view similar to that of FIG. 1 but illustrating another embodiment according to the invention;

FIG. 3 is a sectional view through a supporting structure for the nozzle pin of the control valve;

FIG. 4 is a plan view of the supporting structure according to FIG. 3; and

FIG. 5 is a somewhat enlarged plan view of the spray cap also shown in FIG. 2.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS The high pressure dosing apparatus 1 shown in FIG. 1 comprises a housing 2 and a supply chamber 3 for the medium to be applied in precise quantities, for example, to a polishing disk. An inlet opening 4 to the supply chamber 3 is closable by means of a back pressure relief valve 5. The medium to be dosed is introduced into the high pressure dosing device 1 from a container not shown connected to the housing 2 by a conduit 6, whereby the supply direction is indicated by the arrow a.

A spray cap 8 having an outlet opening 7 is connected to the supply chamber 3 by way of a valve disk 9 and an intermediate member 10 in that order. The member 10 in turn is secured to the housing 2, for example by a conventional thread connection. The housing 2 is provided with a bore 18 aligned with the opening 7, and a control valve mechanism 27 is provided in the bore 18. This control valve mechanism 27 comprises a nozzle pin 13 which extends through a hole 11 in an intermediate wall 12 separating the bore 18 from the supply chamber 3. A sealing ring 26 of conventional design surrounds the nozzle pin 13 to seal the supply chamber 3 from the bore 18. The free end 14 of the nozzle pin 13 is positioned to close the outlet opening 7 when said free end 14 rests against a valve seat 15 in the valve disk 9. The outer diameter of the effective valve seat surface 15 is smaller than the diameter of the nozzle pin 13 so that the tip 14 of the nozzle pin 13 is provided with a surface 16, for example a conical surface, which is subjected to any pressure in the supply chamber 3 so that the pressure tends to push the pin 13 r in the opening direction, (i.e., away from the valve seat). In other words, since the pin 13 has a radially extending surface at its end even when it fully closes the valve, the pressure in the chamber urges the pin away from the valve seat. When the pressure in the supply chamber 3 increases and reaches a predetermined value the force effective on the surface 16 pushes the nozzle pin 13 off the valve seat 15 against the force of a spring 17, thus opening the passage through the valve disk 9. When the pressure decreases again in the supply chamber 3 so that the force of the spring 17 exceeds the pressure acting on the nozzle pin 13, the nozzle pin will again be pressed with its conical tip 14 against the valve seat 15 thereby closing the outlet opening 7.

The bore 18 is located adjacent the intermediate wall 12 of the supply chamber 3 opposite the outlet opening 7. The nozzle pin 13 is guided in the intermediate wall 12 and also in the bore 18 as will be described in more detail below. The pin 13 has a counterseat 19 attached thereto, for example, by means of a set screw and one end of the spring 17 rests on the counter-seat 19, so that the spring 17 urges the pin toward the valve seat.

A bushing 20 is threaded into the housing 2 at the end of the bore 18 as shown at 21 and an adjustment screw 23 for limiting the stroke of the nozzle pin 13 is threaded in the bushing 20. The spring 17 extends partially into the bushing 20 and its opposite end rests against the adjustment screw 23. The screw 23 is axially adjustable relative to the bushing 20, the bushing having an inner thread 22 engaging the external threads of the screw 23. Thus, the spring 17 is held between the abutment seat 19 and the inner end of the adjustment screw 23. In order to assure that the nozzle pin 13 is moved into an opening position in response to different pressures which may exist in the supply chamber 3, it is merely necessary to vary the spring force of the spring 17 by means of the adjustment screw 23, so that the adjustment screw 23 is moved to a greater or lesser extent into the bushing 20.

The adjustment screw 23 has a central axial bore 24 through which the end of the nozzle pin opposite its tip extends, so that the bore 24 guides the nozzle pin. The outer end of the nozzle pin 13 may be provided with a knurled knob 25 for controlling movement of the pin 13 by hand The above described valve arrangement comprising the nozzle pin 13 with the conical tip 14 and the spring 17 as well as the bushing 20 and the adjustment screw 23 constitutes the control valve 27. The control valve opens directly when the pressure in the supply chamber 3 exceeds the spring force of the spring 7, and the spring force is adjusted by means of the adjustment screw 23. However, the control valve 27 may also be actuated by hand independently of the just mentioned adjustment since the spring 17 may be relatively soft or weak in spite of the high pressures which may occur in the supply chamber 3 because the area of the pin acted upon by the pressure is small.

The means 28 for producing the pressure in the supply chamber 3 will now be described. These means comprise a cylinder 29 housing a piston 30 which is attached to a piston rod 31. The piston rod 31 extends through a sealing means 32 into the supply chamber 3. The piston 30 is subject to the force of a spring 33 located in a recess 34 of the cylinder 29. One end of the spring 33 rests against the piston 30 and the other end rests against the bottom of the recess 34. The piston 30 is movable between two stops. The upper stop is formed by a bolt 36 which is screwed into the top of the cylinder 29 by means of a knurled screw 35. The lower stop for the piston 30 is formed by the facing surface of the wall 37 of the cylinder 29. The pressure producing means 28 comprises an inlet opening 38 to which, for example, air under pressure is supplied in the direction of the arrow b. The pressure inlet opening may include a conventional three-way valve. Due to the translation ratio resulting from the cross section of the piston relative to the cross section of the piston rod, it is possible to produce a pressure of the desired magnitude in the supply chamber 3. The quantity of material discharged with each working cycle depends on the piston stroke and on the cross section of the piston rod 31, so that the pistonstroke is adjustable as desired by means of the knurled screw 35 and the bolt 36. Thus, the free end 39 of the piston rod 31 enters to a larger or smaller extent into the supply chamber 3 whereby a respective quantity of the material in the supply chamber 3 is displaced and forced out of the outlet 7. The top of the cylinder 29 may be provided with a dial and the knob 35 may be provided with a pointer so that the dial may be calibrated directly in terms of the quantity of material to be discharged.

The high pressure dosing apparatus la illustrated in FIG. 2 differs from the embodiment according to FIG. I particularly in the construction of the pressure generating means 28a and by the fact that the piston rod 31a and the nozzle pin 13a are arrangedtat an acute angle relative to each other. This arrangement has a number of advantages since the space requirement is smaller and since the apparatus is more easily operable. Further, the flow conditions in the supply chamber 3a are more advantageous than in the embodiment according to FIG. -1.

It will be noted from FIGS. 1 and 2 that the same parts of both devices 1 and 1a are designated by the same reference numerals except that the reference numerals of FIG. 2 have been provided with the index a.

The nozzle pin 13a comprises a ball shaped tip 40a rather than a conical tip. In this arrangement the end of the pin has a socket 41a for receiving the ball, the socket presenting a radial surface on the pin upon which the pressure may act. The diameter of the ball tip 40a is larger than the outer diameter of the valve seat surface 15a. The surface portion of the ball 40a which extends above the valve seat surface 15a andwhich extends into the inside of the supply chamber 3a and the surface of the socket 41a which receives the ball 40a at the free end of the nozzle pin 13a form together a surface which is subjected to thepressure prevailing in the supply chamber 3a. Since the nozzle pin 13a is completely smooth and does not have any shoulders inside the supply chamber 3a, it is assured that the pressure which is effective on the just mentioned surface formed by the ball 40a and the socket 41a, a resulting force which upon reaching of a determined pressure lifts the nozzle pin 13a off the valve seat surface 15a against the force of the spring 17a.

The control valve 27a is distinguished from the control valve according to FIG. 1 merely with regard to its dimensions. Further, the control valve 27a is covered by a cup 420 for the knurled knob a so that the latter cannot be operated inadvertently.

The outlet opening 7a of the supply chamber 3a is again located in a spray cap 8a, the plan view of which is illustrated on a somewhat enlarged scale in FIG. 5. The spray cap 8a is held in position together with the valve seat disk 9a by means of a cup screw 43a and an intermediate piece 10a, the piece I012 being secured to the housing 2a, for example, by a threaded connection. The piece 10a has a longitudinal bore 44a.

A bearing member 45a, as shown in FIGS. 3 and 4 is located within the longitudinal bore 44a. The member 45a is preferably pressed into said bore 44a and is provided with a central bore 46a for supporting and guiding the nozzle pin 13a. The bearing member 45a, as may be especially seen in FIG. 4, has a substantially square cross section. The outer longitudinal edges 47a of the square shape are somewhat rounded and rest against the inner surface of the longitudinal bore 44a.

The polishing paste or the like which is to be dispensed from the high pressure dosing apparatus 10 according to FIG. 2 is supplied to the chamber 3a from a pressurized container through a conduit 48a including a stop valve 49a as well as a back pressure relief valve 5a.

The pressure producing means 28a comprises essentially a cylinder 29a with a piston a and a piston rod 31a which is movable into the supply chamber 3a against the force of the spring 33a. However, special features are incorporated in the embodiment according to FIG. 2 with regard-to the construction of the device for the precise dosing of the materials to be dispensed, as will be described in more detail below.

A stop bolt 51a is provided for limiting the stroke of the piston rod 31a. The stop bolt 51a is axially displaceable and rotatable in the head 50a of the pressure producing means 28a. The stop bolt 51a has an outer thread 52a along at least a portion of its length, and this thread cooperates with a threaded bore 53a of a bearing member 540. The member 54a is located in the head 50a of the pressure producing means 28a.

A bearing bushing 55a extends through a bore 57a in the head 50a and the outer closed end of the bushing 55a extends out of the head 50a and is rigidly secured to a knurled knob 58a. The inner end of the bearing bushing 55a has a flange 59a which rests against a shoulder of the bore 57a inside the head 50a. The bearing bushing 55a is surrounded by a sealing ring 60a which prevents a pressure drop inside the pressure generating means 28a.

The bearing bushing 550 further has a pin 61a which extends through a longitudinal aperture 62a in the stop bolt 5 51a whereby the stop bolt 51a and the bearing bushing 55a are secured to each other against rotation. Thus, when the knurled knob 55a is rotated the rotation is also imparted to the bushing 55a and to the stop bolt 51a through the pin 61a. Since the stop bolt 51a is guided in the threaded bore 53a it changes its axial position in response to any rotation, whereby the length of the stroke of the'piston 30a may be adjusted.

The bearing member 54a with the threaded bore 53a preferably comprises a nut provided with axially extending apertures 64a for the passage of air. These apertures 64a permit the entry of the air under pressure from the inlet port 65a into the cylinder chamber 66a of the pressure generator 28a.

As may be seen from FIG. 2, the pressure generator 28a is secured to the housing 2a by a threaded connection and the entire apparatus is provided at various points with conventional pressure sealing means as shown at 70a, 71a and 72a in FIG. 2. The pressure sealing means assure the proper operation of the high pressure dosing apparatus and prevent leakage of the materials and pressure.

Although the invention has been described with reference to the specific example embodiments, it is to be understood, that it is intended to cover all modifications and equivalents within the scope of the appended claims.

What is claimed is:

1. In a high pressure dosing apparatus for dispensing abrasive and polishing material, having a housing with a material supply chamber and a dispensing outlet in said chamber, a bore in said housing extending in longitudinal alignment with said supply chamber, passage means interconnecting said supply chamber and said bore, and acontrol valve mechanism in said housing for normally closing said dispensing outlet, the improvement wherein said control valve mechanism comprises a nozzle pin extending longitudinally through said supply chamber, through said passage means, and through said bore, said nozzle pin comprising a handle end extending out of said housing and a valve closing end located in said supply chamber adjacent to said dispensing outlet for opening and closing said dispensing outlet, a differential surface on said nozzle pin adjacent to said dispensing outlet for lifting said valve closing end of said nozzle pin off said dispensing outlet in response to a given pressure in said supply chamber, said apparatus further comprising control means in said bore and operatively connected to said nozzle pin for varying the pressure response characteristic of said nozzle pin, and pressure supply means operatively connected to said supply chamber for applying said given pressure to said differential surface, said pressure supply means including piston means and cylinder means as well as stop means positioned to limit the stroke of said piston means, said handle end of said nozzle pin outside said housing permitting the manual operation of said nozzle pin independently of said given pressure.

2. The high pressure dosing apparatus of claim 1, wherein said dispensing outlet comprises a valve seat, said control means comprising a spring located in said bore for normally urging said nozzle pin against said valve seat, said nozzle pin having a shoulder within said bore against which the spring rests, and an adjustable stopper means in said bore for biasing the spring against said shoulder of the nozzle pin.

zle pin which extends movably through said hole and said sealing means.

4. The high pressure closing apparatus of claim 2, wherein said adjustable stopper means comprise a bushing in said bore positioned to limit the movement of said nozzle pin in a direction away from said valve seat, and an adjusting screw threaded into said bushing.

5. The high pressure dosing apparatus of claim 4, wherein said adjusting screw has a central aperture, through which said nozzle pin extends out of said housmg.

6. The high pressure dosing apparatus of claim 1, wherein the end of said nozzle pin positioned to engage said valve seat has a conical tip, the diameter of said nozzle pin in said supply chamber being greater than the diameter of said valve seat to form said differential surface.

7. The high pressure dosing apparatus of claim 1, wherein the end of said nozzle pin positioned to engage said valve seat has a spherical shape, the outer diameter of said valve seat being smaller than the diameter of said end of said nozzle pin to form said differential surface.

8. The high pressure dosing apparatus of claim 2, wherein said dispensing outlet comprises an intermediate member connected to said housing, said intermediate member having a longitudinal bore, a spray cap on the end of said intermediate member away from said chamber, cup screw means for holding said spray cap on said intermediate member, said valve seat being positioned between said spray cap and said intermediate member, said nozzle pin extending through said longitudinal bore in said intermediate member.

9. The high pressure dosing apparatus of claim 8, further comprising a bearing member positioned within said longitudinal bore of said intermediate member for supporting and guiding said nozzle pin, said bearing member having a substantially square cross sectional shape with rounded edges engaging the internal surface of said longitudinal bore of said intermediate member.

10. The high pressure dosing apparatus of claim 1,

wherein said pressure supply means comprise means for coupling displacement of said piston means to said supply chamber, said coupling means including a piston rod sealingly extending from said piston means into said supply chamber, said piston means having a reaction surface greater than the cross sectional area of said piston rod.

11. The high pressure dosing apparatus of claim 10, further comprising a head member fixedly mounted on said housing at the end of said cylinder away from said supply chamber, said stop means comprising a bearing member mounted in said head member, a stop bolt threaded into said bearing member and having one end positioned to engage said piston, and means for rotating said stop bolt.

12. The high pressure dosing apparatus of claim 11, further comprising a bearing bushing having an outer end, said bearing bushing being positioned within said head member axially aligned with said stop bolt, said outer end of said bearing bushing extending out of said head member, said head member having an internally extending flange, said bearing bushing further having an externally extending flange engaging said internally extending flange for inhibiting axial movement of said bearing bushing, said stop bolt extending into said bearing bushing, means for coupling said bearing bushing to said stop bolt for rotary movement while permitting relative axial movement of said bearing bushing and stop bolt, and manual knob means on said outer end of said bearing bushing externally of said apparatus.

13. The high pressure dosing apparatus of claim 11, wherein said bearing member comprises a nut having axially extending passages, said pressure supply means further comprising a source of air pressure coupled to said head member for moving said piston means, whereby air pressure from said source reaches said piston means through the passages in said bearing member.

14. The high pressure dosing apparatus of claim 10, wherein said piston rod sealingly extending from said piston means into said supply chamber is positioned at an acute angle with respect to said nozzle pin. 

1. In a high pressure dosing apparatus for dispensing abrasive and polishing material, having a housing with a material supply chamber and a dispensing outlet in said chamber, a bore in said housing extending in longitudinal alignment with said supply chamber, passage means interconnecting said supply chamber and said bore, and a cOntrol valve mechanism in said housing for normally closing said dispensing outlet, the improvement wherein said control valve mechanism comprises a nozzle pin extending longitudinally through said supply chamber, through said passage means, and through said bore, said nozzle pin comprising a handle end extending out of said housing and a valve closing end located in said supply chamber adjacent to said dispensing outlet for opening and closing said dispensing outlet, a differential surface on said nozzle pin adjacent to said dispensing outlet for lifting said valve closing end of said nozzle pin off said dispensing outlet in response to a given pressure in said supply chamber, said apparatus further comprising control means in said bore and operatively connected to said nozzle pin for varying the pressure response characteristic of said nozzle pin, and pressure supply means operatively connected to said supply chamber for applying said given pressure to said differential surface, said pressure supply means including piston means and cylinder means as well as stop means positioned to limit the stroke of said piston means, said handle end of said nozzle pin outside said housing permitting the manual operation of said nozzle pin independently of said given pressure.
 2. The high pressure dosing apparatus of claim 1, wherein said dispensing outlet comprises a valve seat, said control means comprising a spring located in said bore for normally urging said nozzle pin against said valve seat, said nozzle pin having a shoulder within said bore against which the spring rests, and an adjustable stopper means in said bore for biasing the spring against said shoulder of the nozzle pin.
 3. The high pressure dosing apparatus of claim 2, wherein said passage means comprise a wall opposite said dispensing outlet, a hole in said wall axially aligned with said outlet, and with said bore, and means for sealing said hole against said supply chamber and the nozzle pin which extends movably through said hole and said sealing means.
 4. The high pressure dosing apparatus of claim 2, wherein said adjustable stopper means comprise a bushing in said bore positioned to limit the movement of said nozzle pin in a direction away from said valve seat, and an adjusting screw threaded into said bushing.
 5. The high pressure dosing apparatus of claim 4, wherein said adjusting screw has a central aperture, through which said nozzle pin extends out of said housing.
 6. The high pressure dosing apparatus of claim 1, wherein the end of said nozzle pin positioned to engage said valve seat has a conical tip, the diameter of said nozzle pin in said supply chamber being greater than the diameter of said valve seat to form said differential surface.
 7. The high pressure dosing apparatus of claim 1, wherein the end of said nozzle pin positioned to engage said valve seat has a spherical shape, the outer diameter of said valve seat being smaller than the diameter of said end of said nozzle pin to form said differential surface.
 8. The high pressure dosing apparatus of claim 2, wherein said dispensing outlet comprises an intermediate member connected to said housing, said intermediate member having a longitudinal bore, a spray cap on the end of said intermediate member away from said chamber, cup screw means for holding said spray cap on said intermediate member, said valve seat being positioned between said spray cap and said intermediate member, said nozzle pin extending through said longitudinal bore in said intermediate member.
 9. The high pressure dosing apparatus of claim 8, further comprising a bearing member positioned within said longitudinal bore of said intermediate member for supporting and guiding said nozzle pin, said bearing member having a substantially square cross sectional shape with rounded edges engaging the internal surface of said longitudinal bore of said intermediate member.
 10. The high pressure dosing apparatus of claim 1, wherein said pressure supply means comprIse means for coupling displacement of said piston means to said supply chamber, said coupling means including a piston rod sealingly extending from said piston means into said supply chamber, said piston means having a reaction surface greater than the cross sectional area of said piston rod.
 11. The high pressure dosing apparatus of claim 10, further comprising a head member fixedly mounted on said housing at the end of said cylinder away from said supply chamber, said stop means comprising a bearing member mounted in said head member, a stop bolt threaded into said bearing member and having one end positioned to engage said piston, and means for rotating said stop bolt.
 12. The high pressure dosing apparatus of claim 11, further comprising a bearing bushing having an outer end, said bearing bushing being positioned within said head member axially aligned with said stop bolt, said outer end of said bearing bushing extending out of said head member, said head member having an internally extending flange, said bearing bushing further having an externally extending flange engaging said internally extending flange for inhibiting axial movement of said bearing bushing, said stop bolt extending into said bearing bushing, means for coupling said bearing bushing to said stop bolt for rotary movement while permitting relative axial movement of said bearing bushing and stop bolt, and manual knob means on said outer end of said bearing bushing externally of said apparatus.
 13. The high pressure dosing apparatus of claim 11, wherein said bearing member comprises a nut having axially extending passages, said pressure supply means further comprising a source of air pressure coupled to said head member for moving said piston means, whereby air pressure from said source reaches said piston means through the passages in said bearing member.
 14. The high pressure dosing apparatus of claim 10, wherein said piston rod sealingly extending from said piston means into said supply chamber is positioned at an acute angle with respect to said nozzle pin. 